58 TESTING MISCELLANEOUS SUPPLIES. 



5. Reaction of Oil. 



Heat about 20 grams of the oil with 50 cc of water, daw off the water and 

 test its reaction with litmus. If the reaction is acid it is probably due to sul- 

 phuric acid ; test with barium chlorid. 



6. Action on Copper. 



Spread some of the oil on a bright polished piece of copper and expose to the 

 air for twenty-four hours. The copper should not corrode or turn green. 



7. Tarry and Suspended Matter. 



Place 5 cc of the oil in a pear-shaped separatory funnel of about 200 cc 

 capacity, add 95 cc of gasoline, shake well, and allow to stand fifteen minutes. 

 No precipitate should appear. 



8. Cold Test. 



Warm the oil up to 80 C., and if it contains any solid particles keep at 80 

 until they are completely melted. Put 50 cc of the oil in a dry, 4-ounce bottle, 

 provided with a stopper through which passes a thermometer. Place in a 

 freezing mixture and stir gently with the thermometer until the oil is frozen, 

 insert the cork, and leave the bottle in the freezing mixture for an hour. Then 

 remove from the bath, wipe dry, and place in a beaker packed with dry asbestos 

 to insulate the sides of the bottle. Break up and stir the oil with the ther- 

 mometer; invert the bottle at every degree of rise in temperature, and note 

 the temperature at which the oil will flow from one end of the bottle to the 

 other in fifteen seconds. For the freezing mixture for temperatures above 2 C. 

 use ice and water, for lower temperatures use ice and salt, or, if necessary, 

 crystallized calcium chlorid and snow or shaved ice. 



9. Volatility. 



Heat from 0.5 to 1.5 grams of oil in a flat-bottomed dish in a bath at the 

 temperature of boiling water for four hours. 



10. Fatty Oil. Qualitative Test. 



I I <>at 4 or 5 cc of the oil in a test tube with a piece of caustic soda (solid) for 

 fifteen minutes at a temperature of 230 to 250 C. Allow to cool. The presence 

 of fatty oil is indicated by the gelatinizatiou, complete or partial, of the con- 

 tents of the tube. 



11. Quantitative Determination. 



In tho prosonoo of largo quantities of minernl oil, sjiponifiention with alco- 

 holic potash takes M long time, since the mineral oil prevents the potash coming 

 in '"mart with tin- fjitty oil. Schreiber's method gives good results in a short 

 time. Weigh 5 grams of the oil in a 200 cc Erlenmeyer flask, add 25 to 50 cc 

 of half-normal alcoholic potash and sufficient benzol (CeH) to dissolve the oil 

 \vln-n warmed (generally *2r> cc is enough, but with heavy cylinder oils as much 

 as 50 cc may be necessary ; in this case it is well to add 25 cc of neutral alcohol). 

 Connect the flask with a 3-foot condenser and set it on the iron plate that forms 

 the top of the steam bath, so that the steam will not strike it directly, and regu- 



J. Amer. Chem. Soc., 1907, 2 : 74. 



